Abstract: Objective Using Growth differentiation factor GDF-5 in combination with dexamethasone (Dex) to induce BMSCs into cartilage differentiation and to explore the role of Wnt/β-catenin signaling pathway in cartilage differentiation of rBMSCs.Methods BMSCs were collected from Sprague Dawley rats.The Morphology was observed under inverted microscope .rBMSCs at passage 3 were divided into 6 groups: BMSCs group，BMSCs+Dex group，BMSCs+GDF-5 group,BMSCs+ GDF-5+Dex group，BMSCs+ GDF-5+ Dex+SB216763 group,BMSCs+GDF-5+Dex+ XAV-939 group and induced for 14 days.Alcian blue stain was used to show the changes of proteoglycans ; RT-PCR was used to detecte the mRNA expression of Aggrecan,COL2,Sox9,COL1,Dvl1,Gsk3β and β-catenin.The protein expression levels of COL2 and β-catenin were detected by Western blot. Results Compared with the BMSCs group, BMSCs+GDF-5+Dex group showed deeper proteoglycan staining; Aggrecan, COL2, Sox9 and the protein expression levels of COL2 were significantly increased;β-catenin mRNA and protein expression levels also increased. Compared with the BMSCs + GDF-5 + Dex group,in adding SB216763 group proteoglycans, collagen type Ⅱ gene and protein expression were increased significantly (P <0.05); On the contrary,in adding XAV-939 group cartilage differentiation gene and protein expression were decreased (P <0.05).Conclusion GDF-5 in combination with dexamethasone (Dex) can induce differentiation of rat BMSCs into cartilage, Wnt/β-catenin signaling pathway may play a promoter role.

Key words: Key words: Wnt/β-catenin , BMSCs, Chondrogenic differentiation, GDF-5